<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            width: 300px;
            height: 300px;
            background-color: aquamarine;
        }
        button{
            width: 50px;
            height: 50px;
        }
    </style>
</head>
<body>
    <div></div>
   <div></div>
    <button>按钮</button>
  <script>
      console.log("你是傻逼")
      let  div =document.querySelector("div");
      let  btn =document.querySelector("button");
      btn.onclick=function(){
          div.style.background="red"
      }
  </script>
</body>
</html>